const path = require('path');

const str = '/path///normalize/hi/..';
// const res = path.normalize(str);
// const res = path.join('/hello','///world');
// const res = path.dirname('/src/view/index.html');
// const res = path.basename('/src/view/index.html', 'index');
const res  = path.extname('/src/view/index.js');

console.dir(res);